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Old 03-09-2015, 06:21 PM   #61
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doesn't creep usually create peak torque? unless you dropped timing an insane amount or something weird
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Old 03-09-2015, 07:37 PM   #62
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No it doesn't.

Most of my stock motor builds creep up to 17 or 18 psi at redline intentionally using ebc and peak torque is still below 5000rpm like everyone else's.

Last night I spent close to an hour pulling torque out of the 4500rpm area of a VVT turbo NA, which made 280rwhp, because that's where peak torque waseven with 100% wastegate Duty Cycle from 5500rpm onwards.
We had to use VVT, timing and boost to pull that 4500rpm peak out of the tune, because VE.

Dann
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Old 03-09-2015, 07:42 PM   #63
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creep using ebc? so it's intentional?
if you're inentionally shutting the wastegate up top to create more boost that's not the same as creep.

the only cars I've seen creep to redline are hondas that have insane VE to begin with. maybe I'm wrong
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Old 03-09-2015, 07:53 PM   #64
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The engines torque output doesnt give a **** if its creep due to a low flowing wastegate port or due to a flapper being intentionally closed with EBC.

Yeah Im creating creep intentionally. The above example is a built engine, raced with a 5 speed, so we are using what is effectively creep to keep torque flat as possible but below a threshold.

Even using a huge amount of creep torque peak is still in the normal spot and this is literally a good thing for performance, and not a bad thing for reliability, unless you have some issue like a fuel system that cant keep up or a lead foot and no driver skills.

Dann

Last edited by nitrodann; 03-09-2015 at 08:04 PM.
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Old 03-09-2015, 08:17 PM   #65
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Quote:
Originally Posted by nitrodann View Post
The engines torque output doesnt give a **** if its creep due to a low flowing wastegate port or due to a flapper being intentionally closed with EBC.

Yeah Im creating creep intentionally. The above example is a built engine, raced with a 5 speed, so we are using what is effectively creep to keep torque flat as possible but below a threshold.

Even using a huge amount of creep torque peak is still in the normal spot and this is literally a good thing for performance, and not a bad thing for reliability, unless you have some issue like a fuel system that cant keep up or a lead foot and no driver skills.

Dann


When I ran the 6758 on just the 7psi spring pressure, it peaked at 12psi at peak power and tapered off from there.
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Old 03-09-2015, 08:20 PM   #66
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My point is who cares and why do they care.
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Old 03-09-2015, 08:21 PM   #67
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Quote:
Originally Posted by nitrodann View Post
The engines torque output doesnt give a **** if its creep due to a low flowing wastegate port or due to a flapper being intentionally closed with EBC.

Yeah Im creating creep intentionally. The above example is a built engine, raced with a 5 speed, so we are using what is effectively creep to keep torque flat as possible but below a threshold.

Even using a huge amount of creep torque peak is still in the normal spot and this is literally a good thing for performance, and not a bad thing for reliability, unless you have some issue like a fuel system that cant keep up or a lead foot and no driver skills.

Dann
by definition, what you're doing is not creep.
creep is what happens when you can't control it, and it usually happens at peak torqure, because boost usually creates torque.
"intentional creep", is not creep. it's just boost control
basically what Leafy said. you're missing the point
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Old 03-09-2015, 08:23 PM   #68
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What is the point and why.

Seriously, spell the point out and justify it.
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Old 03-09-2015, 09:04 PM   #69
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lolol
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Old 03-09-2015, 09:58 PM   #70
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In Australia do the turbos spin the opposite direction?
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Old 03-09-2015, 10:03 PM   #71
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After doing dozens of tunes on cars where we need to limit torque for engine and or gearbox reliability, the only way that 'boost creep is bad because boost makes torque' could possibly make sense in this context is if you hadnt calculated a creeping cars torque across the area where it creeps during dyno tuning.

Im putting that to the non believers, and Im asking them to please dispute it.

Dann
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Old 03-09-2015, 11:37 PM   #72
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Quote:
Originally Posted by Corky Bell View Post
BH2dKeith,

No A/O for you until the cast manifold is in my hands. The pattern has been at the foundry long enough to expect castings within a couple weeks.

Your turbo will need a few mods. You or me? If you do it, you will do it as I suggest.
I will be glad to fix it up, nc. What fuel system are you using? Need EGR?

Sorry about no Christmas card. It was just a bigger risk than I was willing to take.

Hang loose, you are at the top of the list. I'll need to figure out which list that was.

corky
This actually makes me feel a bit better.

What needs to be done to the turbo to make it fit? Swap exhaust housing to a conventional one instead of the V-band? If so, I can handle that myself if parts are supplied. You had me re-clock the compressor housing and grind a bit on the compressor housing to get it to fit under the old tubular manifold, so I can handle re-clocking of the compressor housing also. If it is more complicated than that, I can send it your direction.

I have an upgraded fuel pump, 1000cc injectors Megasquirt3 and am running E85.

No EGR on my setup.

Probably on top of your **** list right now If all of this works out, you will end up on my Christmas card list.

Keith
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Old 03-09-2015, 11:42 PM   #73
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Quote:
Originally Posted by nitrodann View Post
Seriously, why do we give a **** if we get 5psi of creep past peak torque?
If your goal boost is 12 psi, and putting a 7 psi spring in your external wastegate results in peak boost of 12 psi, then you end up giving up a lot of spool to keep your peak boost at a reasonable level. Your wastegate will start opening at around 4 or 5 psi with a 7 psi spring, and as soon as the wastegate starts cracking open your spool goes to ****.

Keith
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Old 03-09-2015, 11:47 PM   #74
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I'm sorry why is there a 'goal boost' ?

Dann
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Old 03-09-2015, 11:47 PM   #75
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because there is such a thing as stock rods
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Old 03-09-2015, 11:52 PM   #76
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Oh I see.

And a measure of restriction at a given flowrate as opposed to torque is what we use to protect them.
Now I understand!
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Old 03-09-2015, 11:58 PM   #77
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You're trying real hard. And I'm seeing right through it.
Yes, none of us know the difference between pressure and torque. We're all just stupid 'Muricans with rightside-up dyno plots.
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Old 03-10-2015, 12:10 AM   #78
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Seeing through it. Cite your reasons for being scared of boost creep. For crying out loud, Ive dyno'd this **** enough times to have no reasons myself.
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Old 03-10-2015, 12:16 AM   #79
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Someone should probably explain the difference between boost overshoot and boost creep. I'm pretty sure Dann is referring to creep (boost rises with RPM regardless of wastegate spring pressure), while everyone else is referring to overshoot (boost rises rapidly past the wastegate spring pressure which creates torque spikes that can damage stock engines).
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Old 03-10-2015, 12:22 AM   #80
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Thats correct.

Ive never seen overshoot on an MX5 with a T2x turbo or EFR using competent boost control, and CERTAINLY not with only the wastegate can for boost control.

Dann
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